Paystation adapter for telephone systems



May 31, 1960 Filed Jan. 31, 1957 R. K. KAYE PAYSTATION ADAPTER FORTELEPHONE SYSTEMS 3 Sheets-Sheet l PPUT I l min |03\P I I I l LC IO MFIG. I

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INVENTOR. ROBERT K. KAYE May 31, 1960 R. K. KAYE PAYSTATION ADAPTER FORTELEPHONE SYSTEMS 3 Sheets-Sheet 3 Filed Jan. 31, 1957 U Om 'withoutsacrificing the number tion adapters. I accomplish these and otherobjects in a telephone sys- 2,938,953; ADAPTER 50R TELEPHONE M 1PAYSTATION i srsrn Robert K. Kaye, Rochester, N.Y.,' nssignor to General Dynamics CorporatiomRochester, N.Y., a corporation of DelawareFiled Jan. 31, 1957, set. No. 637,555

5 Claims. 01. 179-163) My invention relates to dial telephone systems ingeneral and more particularly to paystation adapters suitable for use ina dial telephone system where postpay type coin stations are used.

' In a dial telephone system involving both subscriber and paystationlines, it is the practice to provide switching apparatus, such as thewell known step-by-step type line .finder and directively operableselector and connector, for extending connections from a calling line toa called one of the lines. In the case of calling paystation lines,where the coin controlled telephone is of t he postpay type, it isnecessary to allow a connection to be extended from the callingpaystation through the switching apparatus to thecalled line prior tothe deposit of the coin at the paystation. In orderto prevent aconnection from being extended and a conversation being heldbetween thecalling paystation and the called line station without the deposit of acoin, it has been the practice to-insert a so-called paystation adapterof the type disclosed in Patent.2,367,769, Goddard, between the linefinder and the other switching apparatus. Thus, a postpay .paystationadapter is arranged to open a connection entendedthrough the switchingapparatus and to reclose the connection upon the deposit of the requiredcoin at the paystation in order to allow conversation to take place onlyafter the coin has been deposited. In the past, such paystation adaptershave employed means for detecting supervisory signals from the calledline which operates to indicate the completion of a connection betweenthe calling and called lines. The supervisory signal detecting means insuch an adapter re- ;mains effective even after the deposit of a coin atthe calling paystation. This necessitates making the coinresponsiveyapparatus, which is eifective for inactivating the splittingapparatus, additionally effective to prevent further operations of thesupervisory means to thereafter influence the operation of the splittingapparatus. Further, when the supervisory signal detecting means takesthe conventional form of a polarized relay having at least one windingin series with the talking conductors of the :paystation line, thepresence of the relay winding in the talking circuit reduces thetransmission efliciency between the calling, and called stations. eAccordingly, it is an object of my invention .to provide a new andimproved paystation adapter.

Another object of my invention is to provide a new and improvedpaystation adapter having fewer components of functions or accuracy ofoperation. I w l Another object of my invention is to provide apaystation adapter which introduces no loss in transmission level overand above the losses normally present in conventional telephone systemswhich do not include paystatem having a line with a paystation connectedthereto iandlaipluralityof other lines. The system also hasmeansincluding switching apparatus such as a line finder removed fromits for operating line relay 2,938,953 Patented May 31, 1960 .ingcontrol means including'means normally in series with the talkingconnection is enabled in response to the transmission of the supervisorysignal from the called one of the lines. The connecting means isoperative for blocking the talking connection established between thecalling paystation and the called one of the other lines. Other meansthereafter -responsive to the deposit of a coin at the paystation is elfective for disabling the series connected means for the duration of thecall, so that the connection established through the switching apparatusis reestablished only upon the deposit of a coin at the callingpaystation;

For a better understanding of my invention, reference is made in thefollowing description to the drawings attached .to and forming a partofthis specification, and in which: i

Fig. 1 shows in skeletonized form a pa ystation, a paystation line, anda line circuit as well as a block representation of a step-by-step typeline finder; V

Fig. 2 shows inschematic form a paystation adapter; and

Fig. 3 shows a skeletonized representation of a stepby-step typeconnector and block representations of subscriber lines, line circuits,and stations. Power for operating the apparatus described in thefollowing paragraphs is drawn from a 48 volt battery. The battery isarranged so that the most positive terminal or plate is connected toground and is hereinafter referred to as groundland in the drawings asThe most negative, ungrounded plate or terminal of the battery isreferred to in the following paragraphs as battery andin the drawings asl l Referring to Figs. 1 and 3, the system forming the preferredembodiment of my invention includes a plurality of lines, such as L30and L31, of the subscriber: class to which stations B and C,respectively, are connected and lines such as L10 of thepaystation classto which postpay type paystations of the type described in Patent2,367,769, Goddard, are connected. In the following paragraphs 1' willfirst describe the extension of a connection from a calling paystationsuch as A to a called subscriber station suchas B. In thefollowingdscription, the operation of the switching apparatus isconfined to general terms except in those places where the operation ofthe switching apparatus effects the operation of the apparatus formingthe embodiment of my invention because the switching pparatus is wellunderstood by those skilled in the telephone art. A a

To originate a call, the "telephone at paystation A is hooks'witch,thereby actuating means including well knownliookswitch contacts H10 inorder to complete a short between conductors 10a and 10b of line L10.The completion ofthe connection is effective llflwi-thin line circuitL010 in which line L10 terminates. The operating circuiti is traced frombattery through the winding of relay l lll, break contacts 102,conductor 10b, .dial contacted), contactsCSlO, 'n'owclose'd hookswi-tchcontacts H1 0, conductor 10a, and break con tacts 101 to ground. Relaythereupon operated- The operation of relay 110 is elfective for causingotlier apparatus, not shown, to assign an idle one of thedinks withinthe dial oilice switching apparatussuch its "line finder L F to theincoming call on line L10. Line be understoo d that line finder'1LF 10might insteadibe connected through the adapter of Fig'.;2-to a firstselec tor having-access to connectors C'1 R30 through own multiple bankor through any number of intermediate selectors accessible from thefirst selector multiple bank without departing from the spirit or-my?invention.

The advance of the. 'iper'set of line finder LF10 to the terminal setindividual to line L10 is effective for completing a loop circuit fromthe station A telephone to the talking channel of connector CTR30. Theloop circuit is'traced from" conductor T20 through break contacts 231(which are in parallel with the upper winding of relay 260 andcapacitorC21), break contacts 202, conductorTlO, wiper W10, conductor 10a, thestation A telephone including the above-described short, conductor 10b,wiper Wll, conductor R10, break contacts 209, and break'c'ontacts232-(which are in parallelwith the lower winding of relay 260 andcapacitor C22) to conductor R20. 1 It is pointed out that the portion ofthe loop circuit lying within the paystation. adapter may beconsideredto be a talking channel having an incoming endincludingconductors T10 and R10, and an outgoing end includingconductors T20 and R20.

'--Withinconnector CTR30, the'positive and negative terminals of the 48volt battery are connected to the loop circuit through theupper'andlower windings of relay 310 at'break contacts 302 'and 304,respectively. (hirrent from the battery flowing in this first directionthrough the loop circuit energizes'the transmitter TR10' at stati'on-Aand operates relay 310. Within the talking chan- I nel of the paystationadapter, polarizing means comprising rectifiersRCTZl and RCT22, whichare in parallel with the upper and lower windings, respectively; ofrelay 260,"are' poled in a direction to pass current when currentflowsin the aforementioned first direction in the loop circuit. The operationof relay 310 operates release delay relay 320 by closing an obviousenergizing circuit at make contacts 311. The operation of relay 320 iseifective, among other things, to pass-back ground from-make contacts321 over sleeve conductors S20 and S10 to the winding of cutoff relay100 within the calling linecircuit ,LC10. Relay 100 thereupon operatesand completes a locking 'circu'itfor itself through make con- 1tactsf103which are in parallel withirnake contacts 111. 'The'operation of relay100'is thereupon effective for disconnecting ground from conductor 10aat break contacts *101'the Winding of relay ,110frorn conductor 10b atbre'ak'conta'cts 10,2, 2 Relay 110 thereupon releases.

However, relay 100 continues to remain in its operated condition overthe above mentioned locking circuit until ground is removed fromterminal ST10.

, Returning to the consideration of line finder LF10,

the advance of wiper W13 into engagement with terminal HST10 of the'paystat-ion line circuit LC10 is eifective'for completing a signalingcircuit over conductor -I-lS10 between the line circuit and thepaystation adapter to indicate to"the paystation adapter that thecalling line is of the paystation class; To this end all paystation linecircuits are characterized by the presence of ground on the terminalcorresponding to terminal HST10, while lines of the subscriber classhave no such ground-connection ,onthe corresponding terminal. The groundsignal applied to'wiper W13 and conductor H810 is effective .foroperating coin marking relay 230 within the pay- .fs tationadapter overan obvious circuit.

QPQI KiQH 9i H ey 230 is effective for removing 2,938,958 r V h t H 7RCT21 and RCT22 at break contacts 231 and 232, respectively. Thereuponrectifiers RCT21 and RCT22 are effective to make relay 260 respond as apolarized relay, i.e., to release orremain unoperated in response to thepassage of current through the-loop circuit in the first direction andto operate vin response to the a passage through the loop circuit ofcurrent of the same value flowing in the opposite direction. I Aspreviously mentioned, the rectifiers 'ar'elpoled to be conducting whencurrent flows through the loop circuit in the above described firstdirection so that the windings of relay 260 are shorted out. Thus; relay2601 is prevented from'operating at this time. M

Connector CTR30 thereafter responds to trains of directive impulsestransmitted over the loop circuit from dial contacts D10 at callingpaystation A in order to advance the wiper set' of connector CTR30,indicated collectively as W30, into engagement with the connector bankmultiple terminal set corresponding to the called line. When the wiperset has been so advanced, a connection isthereafter'completed from theabove described loop circuit to the conductors of the called-line andcalled line station,such as line L30 and station B, respectively. Whenthe telephone at called station B is answered by removal fromitshookswitch, an off-hook'supervisory "signal is. transmitted over lineL30 to connector CTR30.

Within connector CTR30, supervisory signal responsive means includingrelay 300 is operated in response to the transmission of the off-hooksignal.

-rent flow in the calling line loop, polarizing rectifiers -RCT21 andRCT22 are no longerconductive-sothat current flowing in the loop circuitmust now flow through 'the' windings of relay 260. Therefore relay 260operates at this time. The operation of relay'260 is effective-forclosing an obvious operating circuit for supervisoryrepeater relay 250at make contacts 261. Relay 250 thereupon operates. i I i The operationof the adapter supervisory means including relay 250 is effective forinitiating" the operation of the adapter circuit connecting andsplitting'means including relay 200 by first operating coin detectingrelay 240. The operating circuit for the latter relay is completed fromground through make contacts 251, break contacts 205, and the winding ofrelay 240 to battery. 7 .The op eration of relay 250 is also effectivefor preparing anoperating circuit for splitting relay .200 at' makecontacts The operation of relay 240 is effective for completing anoperating circuit for holding relay 210 from ground through makecontacts 242, break contacts 207, and the lower winding of relay 210 tobattery. Relay 210' thereupon operates with effects which are to beexplained presently. Thereafter, the operation of relay 240 is effectivein response to theo peration of'relay 250 for nection with the batteryconnected winding of relay 240,

and the ground connected upper winding of relay210 by waygof the.calling line in order to hold relays, 240 and :210operated.v Thisholding circuit is traced from batat-teases tery through the winding ofrelay 240, make contacts 204, the above-described loop circuit, makecontacts 209a and 213, and the upper winding of relay 213 to ground.Current flowing through the last traced circuit is sufficient tomaintainboth the low resistance relay 240 and the medium resistance relay210 intheir operated conditions. a i The operation of relay 200 is furthereflective for disconnecting the incoming from the outgoing end of thepaystation adapter talking channel at break contacts 202 and 209 inorder to open the connection previously established between calling lineL andcalled line L30. In order to prevent the release of that portion ofthe switching apparatus lying between the adapter and the called lineconnector terminal set, the operation of relay '200 is further effectivefor completing a holding circuit for maintaining calling bridge relay310 operated. The 'holding circuit includes a short connected betweenconductors T and R20 which is traced from ground through the upperwinding of relay 310, make contacts 301, conductor R20," the lowerwinding of relay 260, make contacts 208 and 212, resistor R21, makecontacts 203, theupper winding of relay 260, conductor T20, makecontacts 303, and the lower windin'g of relay 310 to battery. Relay 260is also maintained operated over the holding circuit so that relay 250is held steadily operated at this time. i

The operation of relay 200 is further eifective for cornpleting' alocking circuit foritself from battery through the winding ofrelay 200,make contacts 206, and break contacts 222 to ground conductor S20, sothat relay 200 is thereafter maintained operated independently of theoper-ationof either relay 240 or relay 250. The operation of relay 200is further effective for. preparing an operating circuit for splitrelease relay 220 at make contacts' 20912. The operation of relay 200 isfurther effective for connecting coin box tone to the calling line loopcircuit including conductor T10 through capacitor C20 and make contacts101; Coin box tone,heard in the receiver, at calling station A informsthe user of the station that the system is in condition to respond tothe'depositof a coin at the paystation.

. aUpon the deposit of a coinwithin the coin receiving apparatus at thepaystation, coin signaling contacts C810 -are:momentarily opened inorder to insert resistor CR10 in series with the above-traced loopcircuit (whichis now connecteditothe windings of relays 240 and 210 inthe above-described manner). The resulting decrease in current flowthrough the windings of relays 210 and240'is Sufficient to release relay240. However, the decreased current is still sufiicient to. maintain themedium resistance of relay 210 in its operated condition. Relay 240 ispart of means also including relay 220 which operates in response to thedeposit of a coin at calling paystation A.

:The further operation of the coin'deposit-responsive. means is nextdescribed. The release of relay 240 is eifective in response to theoperation of relays 200 and 250 for completing an operating circuit forsplit release relay 220 which is traced from ground through makecontacts 251, break contacts 244, make contacts 209b, break contacts225, andthe winding of relay 220 to battery. Relay 220 thereuponoperates. The release of relay 240 is also efifective -for opening theabove-traced operating circuits for relays 200 .and210 at make contacts241 and 242, respectively. However, opening the last named circuits -is;without effect at this time, because the previously described holdingcircuits for the both relays are still effec- .tive 1 [operation ofrelay 220 is efiective for shorting out the; upper and lower windings ofrelay 260 at make contacts 2 21'and 224, respectively. Relay 260releases in .filufizlingxrelays 250and 26 0. The. operation of relay 220is further effective for opening the above=traced holding eircuitgforrelay 200. at break contacts 222' in order to after remains operatedprder=-t o.;st art.the release of the supervisory means inof a telephonesystem in which no a restore the connecting and splitting meansincluding relay 200 to normal. Theefiect of releasing the supervisoryand splitting means is next explained. i i The shorting out of thewindings of relay 260 in the above described manner is efiective forcausing relay 260 to release. Thereupon the above tracedoperatingcircuit for relay 250 is opened at make contacts 261. Relay 250thereafter releases. The release of relay 250 opens theflabove-tracedoperating circuits for relays 200 and 240 at makecontacts 252 and 251,respectively. The latter relays thereupon release. Thereafter thesupervisory means including relays 260 and 250 are inoperative so longas relay 220 remains in its operated condition. The release'of relay 200is effective for recompleting the connection between the incoming andoutgoing ends of the paystation adapter at break contacts 202 and 209 inorder to re-establish the connection between calling line L10 and calledline L30. The release of relay 200 is also effective for opening theabove-traced holding circuit for relays 240 and 210 at make contacts 204and 209a, for opening its ownlocking circuit at make contacts 206b, andfor-removing the connection between the coin box tones'ource and thecalling line loop circuit at make contacts 20l. p, Returning totheconsideration of relay 220, the operation of relay 220 is further eflective for completing a locking circuit for itself from groundedconductor S20 through make contacts 226 and the winding of relay 220 tobattery, and for opening the above-traced operating circuit for itselfat break contacts 225. Relay 220 thereuntil ground is removed fromconductor S20. i i

The continued operation of relay 220 is effective for insuring that thesupervisory means including relays 260 and 250 remain thereafterunoperated during the course of the extension of a call from station Ato station B.

By preventing the reoperation of the supervisory means,

the reoperation of the splitting and coin detecting means is alsoprevented. By shorting out the windings of supervisory relay 260, theattenuation introduced in the paystation adapter talking channel part ofthe transmission path between the calling station A and called station Eis removed. For that reason the paystation adapter employing myinvention has the same loss characteristics paystation adapter -isincluded. it i I L From this point the call between the callingpaystation and the called station E proceeds until the connection isreleased by the restoration of the telephones to their respectivehookswitches. The release of the connection is to be describedpresently.

Returning to the point in the description where splitting meansincluding relay 200 has operated in order to connect the windings ofrelays 240"and 210 in series, provision is made to prevent the user ofthe paystation A telephone from attempting to hold a conversation withthe called station without depositing a' coin where the attempt takesthe form of a momentary operation of the paystation A hookswitch.Operation of the hookswitch momentarily opens the paystation loopcircuit at hookswitch contacts H810. As in the above described case,relay 240 releases. In addition, the opening of hookswitch contacts H10also opens the holding circuit including the upper winding of relay 210,so that relay 210 also releases at this time. The release of relay 210is effective for opening the above described holding circuit for relay310 within connector CTR30 including resistor R21 atmake contacts 212.Meanwhile, the release of relay 210 is eifective in response to theoperation of split release relay 220 for closing an alternate holdingcircuit for relay 200 in order to insure that the re-establishment of aconnection between the calling line loop circuit and the talking channelof connector CTR30 s ad on until '7 ground through break contacts 211,make contacts 223 and 206, and the winding of relay 200 to battery,Thus, relay 200 is maintained in its operated condition so long asrelay'220 is held'o perated [With the holding circuit for relay 310opened, connector CT R30 thereafter releases in the next describedmanner.

At the conclusion of the extension of'aconnection from paystation A tocalled station B, or upon an attempt to avoid payment for the call byopening the hookswitch contacts at the calling paystation inthe abovedescribed manner, a disconnect signal is transmitted to connector CTR30in the form of a prolongedopening of either of the above describedcircuits used for placing a short between conductors T20 and R20. Inthis manner, calling bridge relay 310 is released to open the operatingcircuit of slow releasetype relay 320 at make contacts 311 for aninterval of time suificient to allow relay 320 to release. Otherapparatus well understood ,by those skilled in the art is energized inresponse to the release of relay 320 for restoring wiper set W30 ofconnector CTR30 to its normal position, thereby opening the connectionbetween connectors CT-R30 and the called line and station. The releaseof relay 320 is; further effective for; opening'the ground connection toconductor S20 at makecontacts .321. Thereupon the locking circuit ofsplit release relay 220 within the paystation adapter is opened andthepreviously, mentioned operating circuit; for cutofi relay 100 incalling line circuit LC is opened, Relays 220 and 100 thereupon release.Similarly, apparatus within line finder .LF10 is released atthis time inorder to restore the wiper set including wipers W10-W13, inclusive, toits normal position in order to further disconnect the calling stationline from the switching apparatus of the telephone system .Therestoration of line finder LF10to its normal position opens thepreviously described operating circuit for coin marking relay 230 in anobvious manner. The subsequent release of relay230 restores the shortcircuit-connections normallypresent around the upper and lower windingsof relay 260 at break contacts 231 and 232, respectively. Therestoration of relay 220-to itsnormal condition is efiective for openingthe above described shorts around the upper and lower windings of relay260 .at make contacts 221 and 224, respectively; further, the releaseofrelay 220 is effective forpartially restoring the first describedholdingcircuit for relay 200 by closing break contacts 222 and forrepreparing its own operating circuit by closing break contacts 225.;Thepaystation adapter as well as the preceding line finder LF10 and thesucceeding switching apparatus including connector CTR30 are. now innormal condition and ready for a further use. i V The foregoingdescription has been confined thus lfar to the considerationof a callfrom a paystation line,

such as L10, to another line within the system. The switching apparatusincluding line finder LF10 and connector CTRZaQ) may also be utilizedforextending calls from a subscriber station such as C on line L31 toanother subscriber station line such as L30. In order to extend suchacall, the subscriber at station C removes his. telephone fromitshookswitch in order to energize line circuit LC31 in which line L31terminates in the usual mannor. The energization of line circuit LC3'1is effective for causing an idle line finder such as LF10 to be ad-Nanced so that the wiper set including wipers W10-W13,

inclusive, engages terminal set TS11 on which the conductors of line L31as well as the usual sleeve conductor of line circuit LCM areterminated. Thereafter the call .is extended through line finder LFli)to connector CTR30 in the previously described manner. .In the case ofcalls extended from subscriber line circuits, however, no ground isfound on the terminal engaged by wiper W13, sotl atcoin marking relay230 within the paystation adapter succee'ding linc finderLF10-ren1ains-.,in unoperated condition throughout the extension of acall from' the subscriberline. With relay 230 in its normal condilinesand is made effective only when'calls are "extended a system. I

tion, the abovedesjcribed short normally present around each winding ofrelay 260 insures that relay 260 will remain in its normalconditionthroughout the extensionof the call; Thus the supcrvisory meansincluding relays 260 .line L30. 1 The continued presence of a shortaround the windings of relay 260 maintains the transmission level andcalls extended from one subscriber station to another through theswitching apparatus at the same level that would be maintained in theevent that the paystation adapter were omitted from the above describedtelephone In summary, with the above described paystation adapter,control means is provided to operate in responseto the operation of theswitching apparatus supervisory means, The adapter also includes meansoperative in response to the deposit of a coin at the paystation. Thecontrol meanstincludes meansfor connecting the coin deposit responsivemeans to .the calling paystation line and for blocking'the connectionbetween the'calling and called lines. The control means, also includessupervisory responsive means in the form of a polarized relay having atleast one winding in series with the loop of thecal ling paystation lineand the talking connection est tablished through the switchingapparatus. The polarized relay is arranged to benormally unoperated andto operate in response to the reversal of current flow within ,thecalling line loop circuit which occurs upon, the opera tion of theswitching apparatus supervisory means: The supervisory responsivemeansenables-the .controlrmeans to carry out the above-described functions.Thus, upon the operation of the control means, the coin depositresponsive means operates (when a coin is deposited) to disable thecontrol means. The disabling operation is accomplishedbythe operationofme'ans included withinthe coin deposit responsive vmeans forreleasing" the above. referred to connecting, means to its normalcondition, thereby disconnecting the coin deposit responsivemeans fromthe paystation line and removing the block .in the after, thesupervisory responsive means is inoperative i when subsequentlytransmitted supervisory signals 1 are received at the paystationadapter. The adapter also includes. means for. maintaining the operatedcoin deposit responsive'means in its operated condition for thedurationof-the callso that 'thesupervisory,responsivemeans and .the connectingmeans'are unaflectedby the transmission of supervisory signals from thejcalled line to the switching apparatus throughout the remainder of thecall. In order-to makethe paystation adapter, located'within theswitching apparatus, discriminate between calls extended from paystationand non-paystation lines, means is provided within the adapter to benormally effective for making the supervisory responsive means and,consequently, the control means-inoperative. This is accomplished bymeans independent from the above-mentioned releasing means that wasdescribed as normally effective to constructively disconnect thepolarized relay from the talking connection by shorting out thepolarized relay winding or windings. The independent means is operatedin response to the extension of a call from a paystation line throughthe switching apparatus so that the polarized relay operates upon theopening of the short around its winding or windings. Thus the paystationadapter is'ineifective during the extension of callsfrom subscriberfrom, calling paystation lines. v v i While I have described in theabove-paragraphs the preferred embodiment of my invention, othermodifications of the apparatus will readily occur to those skilled inthe art, I,the reore, aim in the appended claims to cover all suchmodifications as fall within the true spirit and scope of my invention.

Whatis claimed is: 1

1. Ina telephone system, a line comprising conductors having apaystation connected thereto, a plurality of other lines, switchingapparatus directively operable under the control of said paystation forextending a connection from said paystation to a called one of saidother lines, and supervisory means within said switching apparatusoperative in response to the transmission of an offhook signal from thecalled one of said lines; the combination comprising: means including arelay having windings in series with said talking connection forresponding to a signal from said supervisory means, control meansresponsive to the operation of said relay for blocking the talkingconnection established between said paystation and the called one ofsaid other lines, means operative in response to the deposit of a coinat said paystation for shorting out said relay windings in order todisable said relay and for releasing said control means from itsoperated condition, said control means being further operative forconnecting said coin responsive means to said paystation, and meansoperative for maintaining said coin responsive means operativethroughout the duration of the connection.

2. In a telephone system, a line comprising conductors having apaystation connected thereto, a plurality of other lines, switchingapparatus directively operable under the control of said paystation forextending a connection to a called one of said other lines, a battery insaid switching apparatus, a loop circuit including said conductors forextending a connection from said paystation to said battery in order tocause current to flow through said loop circuit in a first direction,means operative in response to the deposit of a coin at said paystation,connecting means for transferring said loop circuit from its connectionto said battery into connection with said coin deposit responsive means,means within said switching apparatus operative in response to thetransmission of an oil-hook signal from the called one of said otherlines for reversing the direction of current flow through said loopcircuit, supervisory means including a polarized relay having at leastone winding in series with said loop circuit operative in response tothe reversal of current flow in said loop circuit for operating saidconnecting means, said coin deposit responsive means being opera-tivefor shorting out said relay winding in order to render said supervisorymeans inoperative with respect to said connecting means, and means forthereafter maintaining said coin deposit responsive means in operatedcondition, whereby said supervisory means is prevented from respondingto further signals transmited from said switching apparatus after thedeposit of a coin at said paystation.

3. In a telephone system including a first plurality of lines havingpaystations connected thereto, a second plurality of other lines, andswitching apparatus for establishing a talking connection between acalling one of said lines and a called one of said lines, thecombination comprising: means including means within said switchingapparatus in series with the talking connection to be enabled inresponse to the transmission of an answering supervisory signal from acalled one of said lines for blocking the talking connection, meansthereafter operative in response to the deposit of a coin at the callingone of said paystations for disabling said series-con nected means forthe duration of the connection, and class of service means within saidswitching apparatus normally efiective for making said series-connectedmeans inoperative, said class of service means being operative inresponse to the extension of a connection from a calling one of saidpaystation lines through said switchof said paystation lines. p c v 4; The system set forth in claim 3 wherein "said eriesconnected means isnormally connected tosaidj switch- .ing apparatus, said coindeposit'responsive meansis also operative for efiFectively disconnectingsaid series-connected means from said switching apparatus, "and saidclass of service means normally constructively disconnects saidseries-connected means from said switching apparatus and is operativefor constructively connecting said seriesconnected means to saidswitching apparatus.

5. In a telephone system including a first plurality of lines havingpaystations connected thereto, a second plurality of other lines, andswitching apparatus for establishing a talking connection between acalling one of said lines and a called one of said lines, supervisorymeans within said switching apparatus operative in response to thetransmission of an answering supervisory signal from the called one ofsaid lines, a paystation adapter within said switching apparatus, saidadapter including control means and means responsive to the deposit of acoin at a calling one of said paystations, said control means havingmeans in series with an established talking connection to be enabled inresponse to the operation of said supervisory means for blocking thetalking connection established through said switching apparatus and forconnecting said coin deposit responsive means to the calling one of saidlines, said coin deposit responsive means being effective for disablingsaid series-connected means and the remainder of said control in orderto make said series-connected means unresponsive to the operation ofsaid supervisory means and to re-establish a talking connection throughsaid switching apparatus, means for maintaining said coin depositresponsive means in operative condition for the duration of theconnection, and class of service means within said switching apparatusnormally effective for making said series-connected means inoperative,said class, of service means being operative in response to theextension of a connection from any one of said paystation lines throughsaid switching apparatus for making said series-connected meansoperative in order to make said connection blocking means elfective onlyin the case of calls extended from calling ones of said paystationlines.

6. In a telephone system; a first plurality of lines having paystationsconnected thereto; a second plurality of lines having subscriberstations connected thereto; each of said lines including a pair ofconductors; switching apparatus directively operable from calling onesof said lines for extending a connection from the calling one of saidlines to a called one of said lines; a battery in said switchingapparatus; a loop circuit including said conductors of the calling oneof said lines for extending a connection from said station on thecalling one of said lines to said battery in order to cause current toflow through said loop circuit in a first direction; a paystationadapter within said switching apparatus including means operative inresponse to the deposit of a coin at a calling one of said paystations,connecting means, and supervisory means; said connecting means beingoperative for transferring said loop circuit from its connection to thecalled one of said lines to said battery into connection with said coindeposit responsive means; means in said switching apparatus operative inresponse to the transmission of an olf-hook signal from the called oneof said lines for reversing the direction of current flow through saidloop circuit; said supervisory means including a polarized relay havingat least one winding in series with said loop circuit and beingoperative in response to the reversal of current flow in said loopcircuit for operating said connecting means; said coin deposit;responsive means operative for shorting out said relay winding in orderto render said supervisory means inoperative with respect tosaidconnecting means following the deposit of-a coin at said paystation; andmeans normally efie'ctive ifons hort'ing' out said relay winding andoperative only during theeritension of a'connec'tion from a calling 'oneof said paystation lines to said switching apparatus for opening the[short around said relay winding; whereby the apparatus within saidpaystation adapterlis efiective only duringfl the extension of callsfrom said anyone of said paystat ion lines.

zeaaess References Cited in the file of this patent f UNITED STATESPATENTS Martin Nov. 22, 1938 Evers Sept. 10', 1940 Brubaker "Apr. 28,1942 Faulkner et al. Jan. 3, 1956 1 King Jan. 21, 1958

